[PATCH] drm/radeon: insist on 32-bit DMA for Cedar on PPC64/PPC64LE

[Ben Crocker]

One of my colleagues did discover a "Radeon HG 5450 PCI" from February
2010 which did, apparently, have a Cedar GPU and very definitely had a
(plain old) PCI connector.

But I take your point, and will just drop the PCI/PCIE check.


On Thu, Feb 22, 2018 at 12:04 PM, Michel Dänzer <michel at daenzer.net> wrote:

> On 2018-02-22 10:57 PM, Ben Crocker wrote:
> > In radeon_device_init, set the need_dma32 flag for Cedar chips
> > (e.g. FirePro 2270).  This fixes, or at least works around, a bug
> > on PowerPC exposed by last year's commits
> >
> > 8e3f1b1d8255105f31556aacf8aeb6071b00d469 (Russell Currey)
> >
> > and
> >
> > 253fd51e2f533552ae35a0c661705da6c4842c1b (Alistair Popple)
> >
> > which enabled the 64-bit DMA iommu bypass.
> >
> > This caused the device to freeze, in some cases unrecoverably, and is
> > the subject of several bug reports internal to Red Hat.
> >
> > Signed-off-by: Ben Crocker <bcrocker at redhat.com>
> > ---
> >  drivers/gpu/drm/radeon/radeon_device.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/radeon/radeon_device.c
> b/drivers/gpu/drm/radeon/radeon_device.c
> > index ffc10cadcf34..ba7435bcd208 100644
> > --- a/drivers/gpu/drm/radeon/radeon_device.c
> > +++ b/drivers/gpu/drm/radeon/radeon_device.c
> > @@ -1397,6 +1397,11 @@ int radeon_device_init(struct radeon_device *rdev,
> >       if ((rdev->flags & RADEON_IS_PCI) &&
> >           (rdev->family <= CHIP_RS740))
> >               rdev->need_dma32 = true;
> > +#ifdef CONFIG_PPC64
> > +     if ((rdev->flags & (RADEON_IS_PCI | RADEON_IS_PCIE)) &&
>
> Cedar is (like all Radeons from the last decade) always PCIe, so this
> flags check is redundant FWIW.
>
>
> --
> Earthling Michel Dänzer               |               http://www.amd.com
> Libre software enthusiast             |             Mesa and X developer
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